docs: def get_cell_boundary_variables(ds):
      '''
      Returns a list of variable names for variables that represent cell
      boundaries through the `bounds` attribute
  
      :param netCDF4.Dataset nc: netCDF dataset
      '''
      boundary_variables = []
      has_bounds = ds.get_variables_by_attributes(bounds=lambda x: x is not None)
      for var in has_bounds:
          if var.bounds in ds.variables:
              boundary_variables.append(var.bounds)
      return boundary_variables